The genetic basis of bovine milk production is of immense significance to the dairy industry. An ability to modulate milk volumes and content has the potential to alter farming practices and to produce products which are tailored to meet a range of requirements. In particular, a method of genetically evaluating bovine to select those which express desirable traits, such as increased milk production and improved milk composition, would be desirable.
To date, bovine genomics are poorly understood and little is known regarding the genes which are critical to milk production. While there have been reports of quantitative trait loci (QTLs) on bovine chromosome 14 postulated to be associated with milk production (Coppieters et al (1998)), the specific genes involved have not to date been identified.
Marker assisted selection, which provides the ability to follow a specific favourable genetic allele, involves the identification of a DNA molecular marker or markers that segregate with a gene or group of genes associated with a QTL. DNA markers have several advantages. They are relatively easy to measure and are unambiguous, and as DNA markers are co-dominant, heterozygous and homozygous animals can be distinctively identified. Once a marker system is established, selection decisions are able to be made very easily as DNA markers can be assayed at any time after a DNA containing sample has been collected from an individual infant or adult animal, or even earlier as it is possible to test embryos in vitro if such embryos are collected.
The applicants have now identified a gene responsible for the QTL effect on bovine chromosome 14 as well as a number of polymorphisms which are associated with distinct genetic merits of animals for milk composition and volume.
It is an object of the present invention to provide an application method for marker assisted selection of this bovine gene, and in particular, of the polymorphisms in the bovine gene which are associated with increased milk volume and altered milk composition; and/or to provide genetic markers for use in such a method; and/or to provide the nucleic acid and amino acid sequences of this gene and encoded polypeptide; and/or to provide animals selected using the method of the invention as well as milk produced by the selected animals; and/or to provide the public with a useful choice.